A ring laser gyroscope is a device used to sense inertial rotation. The gyroscope is a common component in any navigation system, including systems used on aircraft, space craft, watercraft, etc.
Ring laser gyroscopes or gyros are well known in the art and are specifically described in U.S. Pat. No. 3,373,650 to Killpatrick, and U.S. Pat. No. 3,390,606 to Podgorski.
A common problem in ring laser gyros is lockin. Lockin occurs when the gyro sits idle causing the two laser beams within the gyro to lock together and operate at the same frequency. To avoid lockin, an oscillatory input is provided to the gyro. This oscillation is provided by a dither means.
Attaching the dither means to the laser gyroscope block causes problems that seriously affect the operation of the gyro. Differences in the thermal characteristics of the laser block and the mounting structure creates stresses in the laser block.
The laser gyro block is typically made out of glass or some other material having a very low coefficient of thermal expansion. However, the dither motor is typically made of aluminum or metal having a higher coefficient of thermal expansion. It is not feasible to attempt to make the dither motor out of a glass due to the breaking characteristics of glass, nor is it feasible to make the gyro block of metal. Therefore it is necessary to create a configuration for connecting the dither motor and the gyro block that reduces the stress caused by the mismatch in coefficient of thermal expansions.
In the past dither motors have been attached to ring laser gyroscopes in a number of ways. In smaller gyroscopes the dither motor was clamped to the laser gyro block. In larger gyroscopes an internal dither motor is placed in the center of the block and attached thereto. In other configurations, the dither means is attached to the block by a compression fit. Each of these attachment methods creates stresses in the block due to different rates of thermal expansion.
Prior art has used complicated dither motor geometries to alleviate the problems previously mentioned. This solution includes the creation of a void between the laser block and the dither motor to allow for thermal expansion without placing any stress on the gyro block.